Cassia fistula is well known for its laxative and antifungal properties due to anthraquinone compounds in the pods. This study quantitatively analyzed rhein in the C. fistula pod pulp decoction extracts kept under various storage conditions using HPLC. The antifungal activity of the extracts and their hydrolyzed mixture was also evaluated against dermatophytes. The contents of rhein in all stored decoction extracts remained more than 95% (95.69-100.66%) of the initial amount (0.0823 ± 0.001% w/w). There was no significant change of the extracts kept in glass vials and in aluminum foil bags. The decoction extract of C. fistula pod pulp and its hydrolyzed mixture containing anthraquinone aglycones were tested against clinical strains of dermatophytes by broth microdilution technique. The results revealed good chemical and antifungal stabilities against dermatophytes of C. fistula pod pulp decoction extracts stored under various accelerated and real time storage conditions.